(a) Field of the Invention
The present invention relates to a rear warning system for a vehicle and a control method thereof, and more particularly, to a rear warning system for a vehicle with improved performance of detecting an obstacle positioned at a rear of the vehicle closer than or equal to a predetermined distance, and a control method thereof.
(b) Description of the Related Art
In general, a rear warning system for a vehicle is a device mounted on the vehicle and prevents a vehicle accident by providing a notification that an obstacle exists at the rear of the vehicle when the vehicle is reversed. The rear warning system is also called a rear detecting system. Further, a parking aid system (e.g., a parking assist system) is a system that has the same concept as that of the rear warning system. In other words, the rear warning system refers to a system that automatically detects an obstacle positioned at a rear of the vehicle when the vehicle is reversed due to parking or other reasons.
Additionally, an ultrasonic wave sensor is mainly used for the detection of the obstacle. Further, the ultrasonic wave sensor is mounted at a rear bumper of the vehicle. The ultrasonic wave sensor operates when a driver shifts into reverse gear, and when the obstacle is detected closer than or equal to a predetermined distance, and the ultrasonic wave sensor is operated to transfer a warning sound to the driver. Further, when a distance between the vehicle and the obstacle decreases, an interval of the warning sound may be less frequent or a sound of the warning sound may be louder.
Recently, various rear warning systems for the vehicle employing a method of displaying a distance to a rear obstacle via a display device and a method of photographing the rear of the vehicle using an imaging device (e.g., a camera) and displaying the photographed rear have been developed, in addition to a method of a notification of a distance between the vehicle and the obstacle by changing an interval of the sound.
However, when the obstacle positioned at the rear of the vehicle is detected using the ultrasonic wave sensor, the obstacle positioned at the rear of the vehicle may not be detected at a substantially short distance. Particularly, when a distance between the vehicle and the obstacle is equal to or less than about 30 cm, a non-sensed area of the ultrasonic wave sensor may be generated.
Moreover, a detecting sensor approach and an intention of opening a trunk of a user is used in a device, such as a hands-free lift gate, enabling the user to open the trunk of the vehicle without the use of hands. Further, the sensor may be mounted at a rear side of the vehicle.
However, according to the automation of several devices of the vehicle, a considerable number of high-priced sensors are mounted in the vehicle. That is, a manufacturing cost of the vehicle may be increased.
The above information disclosed in this section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.